The present invention is related to an internetwork apparatus for routing packets, and more particularly, to an internetwork apparatus for routing packets using MPLS (MultiProtocol Label Switching). An internetwork apparatus is, for example, a router or a LAN (Local Area Network) switch.
MPLS is a technology currently being developed into a standard by the MPLS working group of the IETF (Internet Engineering Task Force) as a key technology for intranets and the Internet backbone. As documentation related to MPLS, there is, for example, the RFC (Request for Comments) 3031 “Multiprotocol Label Switching Architecture” standardized and made public by IETF.
Label switching technology, featuring high-speed data transmission, scalability, and ease of traffic control, is utilized in MPLS. According to MPLS, FEC (Forwarding Equivalence Classes) are determined by a destination IP (Internet Protocol) address (hereinafter referred to as DIP) included in the IP header of a Layer 3 packet. Further, the same label is attached to each of the packets in a serial packet flow, in which the FEC is the same. The value of the label corresponds to that FEC. A packet attached with a label is routed by an MPLS-supporting internetwork apparatus by referring only to this label.